Xamarin has announced on their blog that the second edition of the Xamarin.Forms book that Charles Petzold is writing is available. All of the source code in the book is also up in a GitHub repository and available for download. They are targeting having a new chapter out every week until the book is finished.
This version has XAML as well as code for creating the Forms as well as comparing them. It also shows how you can have code and XAML working together. It is a really good resource.
Grab your copy over here: